This invention relates to a digital electronic control unit that may include real-time clock-based control, remote control and networking capabilities for controlling the functions of domestic and commercial appliances such as washing machines, refrigerators, dishwashers, electric ovens, and the like.
Many modern appliances incorporate control elements that are common in the nature of their control action as well as the parameters that are controlled. For example, temperature control is a common requirement in several different appliances such as refrigerators, washing machines, dish-washers and electric ovens. Similarly, on-off control of fractional horsepower AC motors is also common to all the appliances mentioned above, besides many others. Timer based control is yet another of the common requirements in many appliances. These requirements extend to several different commercial appliances also.
The control mechanisms currently employed in each of these appliances are often widely different from each other. In addition, there are generally several different control mechanisms employed in each appliances, often as many as one separate control device for each controlled parameter, with each of the control devices being control device for each controlled parameter, with each of the control devices being wired together in a final circuit to perform the desired overall control function in a coordinated manner. This manner of implementation is inefficient and expensive when compared with the capabilities that emerge with the use of an integrated system of control in which the advantages offered by modem electronics technology are utilized to the fullest to provide an integrated, miniaturized implementation that is both cost-effective and efficient in terms of operation, implementation and energy consumption.
Some of the common parameters for control in appliances are:
1) Temperature
2) Liquid Level
3) On-Off control of fractional horse-power ac or dc motors.
4) Time sequences
5) Eventsxe2x80x94such as switch closures/openings.
In addition, some common requirements are:
1) Audio output (e.g. to alert users when attention is required).
2) Push-button/rotary adjustments of control parameters by the user.
3) Display of user-selections/events/parameter values by visual meansxe2x80x94indicators or displays.
An implementation of the various control functions in single-chip form results in a flexible xe2x80x9celectronic control elementxe2x80x9d that provides the maximum advantages of low-cost, small size, ease of implementation and high reliability. There are no known equivalent implementations available today.
Microcontroller-based implementations for some control parameters, such as temperature, are known. U.S. Pat. Nos. 4,158,759, 4,367,387, 4,399,352, 4,066,945, 4,431,893, 4,481,393, 4,504,716, 4,533,810, 4,367,387 and 4,504,716 disclose examples of such electronic controls for various appliances. These come close to realising some of the advantages but fall short in respect of optimal implementation of some of the common requirements, such as triac-firing control, a.c motor protection controls and interfaces to sensors. These requirements generally entail the incorporation of additional external circuitry and interfaces that dilute the effectiveness of the implementation.
Many modem control systems that are used for industrial or commercial applications incorporate the following features:
1) Real-time-clock (Time-of-day) based control actions.
2) Networking of various devices inorder to share resources or data, as well as to provide remote access to a device over the network.
3) Remote control using a hand-held remote control device.
The use of computers in control systems has further increased the need for such intercommunications. Finally, the rapid growth of the Internet and its fast expanding reach into offices and homes in the movement towards the xe2x80x9cnetworked societyxe2x80x9d of the near future is expected to generate the demand for internetworking the various systems. These developments have led to the need for communication abilities even in the average devices of the home. It is therefore expected that domestic appliances would also require such capabilities.
Most designs of devices with such capabilities utilise microcomputers or microcontrollers as the key component for control. While this approach works very well, it is not the most cost-effective or efficient for many applications. In particular, the cost-sensitive, mass-volume application area of domestic appliances require special interface circuits, such as AC power switching devices, for which additional hardware is needed when using microcontrollers. This additional hardware can easily increase the cost and size of the control for the appliance very significantly. The use of special custom hardware provides a better solution, but existing designs of such custom hardware are very specialised to a particular application or appliance. Each appliance product therefore needs its own dedicated design of custom hardware.
The most desirable solution is one in which a specially-designed hardware suitable for the entire range of appliances, is configured for use in each specific product. Such a design would provide the flexibility of microprocessor-based designs at significantly lower cost and size.
The present invention relates to a digital electronic control unit that provides an efficient, miniature, reliable and cost effective control mechanism for use in appliances intended for household and commercial applications, such as washing machines, refrigerators, dishwashers, ovens, and the like. It further relates to a flexible, digital electronic control unit for use in domestic and commercial appliances, that provides the capabilities of real-time clock-based control, remote control and networking.